The present invention is directed to compounds which inhibit the RNA-dependent RNA polymerase (RdRp) encoded by Hepatitis C virus (HCV). The compounds, or pharmaceutically acceptable salts or prodrugs thereof, are of value in the treatment and/or prevention of infection by HCV.
The Field of the Invention. HCV is a major human pathogen, infecting an estimated 170 million persons worldwidexe2x80x94roughly five times the number infected by human immunodeficiency virus type 1. A substantial fraction of these HCV infected individuals develop serious progressive liver disease, including cirrhosis and hepatocellular carcinoma. (Lauer, G. M.; Walker, B. D. N. Engl. J. Med. (2001), 345, 41-52).
Presently, the most effective HCV therapy employs a combination of alpha-interferon and ribavirin, leading to sustained efficacy in 40% of patients. (Poynard, T. et al. Lancet (1998), 352, 1426-1432). Recent clinical results demonstrate that pegylated alpha-interferon is superior to unmodified alpha-interferon as monotherapy (Zeuzem, S. et al. N. Engl. J. Med. (2000), 343, 1666-1672). However, even with experimental therapeutic regimens involving combinations of pegylated alpha-interferon and ribavirin, a substantial fraction of patients do not have a sustained reduction in viral load. In addition, the prospects for development of a prophylactic or therapeutic vaccine appear dim, in spite of intensive research efforts. Thus, there is a clear and long-felt need to develop effective therapeutics for treatment of HCV infection.
HCV is a positive-stranded RNA virus. Based on comparison of deduced amino acid sequence and the extensive similarity in the 5xe2x80x2 untranslated region, HCV has been classified as a separate genus in the Flaviviridae family. All members of the Flaviviridae family have enveloped virions that contain a positive stranded RNA genome encoding all known virus-specific proteins via translation of a single, uninterrupted, open reading frame.
Considerable heterogeneity is found within the nucleotide and encoded amino acid sequence throughout the HCV genome. At least six major genotypes have been characterized, and more than 50 subtypes have been described. The major genotypes of HCV differ in their distribution worldwide, and the clinical significance of the genetic heterogeneity of HCV remains elusive despite numerous studies of the possible effect of genotypes on pathogenesis and therapy.
The RNA genome is about 9.6 Kb in length, and encodes a single polypeptide of about 3000 amino acids. The 5xe2x80x2 untranslated region contains an internal ribosome entry site (IRES), which directs cellular ribosomes to the correct AUG for initiation of translation. The translated product contains the following proteins: core-E1-E2-p7-NS2-NS3-NS4A-NS4B-NS5A-NS5B. This precursor protein is cotranslationally and posttranslationally processed into at least 10 viral structural (core, E1, E2) and nonstructural (NS2-NS5B) proteins by the action of host cell signal peptidase and by two distinct viral proteinase activities (NS2/3 and NS3).
Although the functions of the NS proteins are not completely defined, it is known that NS3 is a serine protease/RNA helicase, NS4A is a protease cofactor, and NS5B is an RNA dependent RNA polymerase involved in viral replication. It has recently been demonstrated that functional NS5B is required for virus infectivity in chimpanzees (Kolykhalov, A. A. et al. J. Virol. (2000), 74, 2046-2051). This result strongly suggests that inhibition of the NS5B RdRp is a viable approach for the development of HCV therapeutic agents.
Description of Related Art. Efforts toward the development of HCV NS5B RdRp inhibitors have resulted in the following disclosures:
Altamura et al. (Istituto Di Ricerche Di Biologia Molecolare) describe diketoacid RdRp inhibitors (WO 00/06529 and WO 02/06246 A1). Altamura et al. suggest that the diketoacids and dihydroxypyriridine carboxylic acids inhibit HCV RdRp by interfering with the binding of phosphoryl groups at the active site of the enzyme.
A series of three disclosures from Viropharma Inc. (Bailey, T. R. et al, WO 00/10573; Bailey, T. R. et al, WO 00/13708; Young, D. C. et al, WO 00/18231) describe HCV RdRp inhibitors. WO 00/10573 covers a series of rhodanine derivatives, WO 00/13708 covers a series of barbituric acid or thiobarbituric acid derivatives, and WO 0018231 covers a series of dihydrobenzothiophene derivatives.
R. Storer (Biochem Pharma, Inc.) has disclosed the use of a series of dioxolane nucleosides for treatment of HCV (WO 01/32153).
EP 1162196 (Japan Tobacco Inc.) discloses a series of fused ring heterocycles as inhibitors of HCV RdRp. These compounds may be distinguished from the applicants"" compounds in the nature of the xe2x80x9cAxe2x80x9d substituent in applicants"" Formula I compounds.
WO 02/04425 (Boehringer Ingelheim) discloses a series of HCV NS5B polymerase inhibitors which also may be distinguished from the applicants"" compounds in the nature of the xe2x80x9cAxe2x80x9d substituent in applicants"" Formula I compounds.
WO 01/85172 (Smithkline Beecham) discloses a series of 1-(alkyl)-3-(1,1-dioxo-2H-benzo-1,2,4-thiadiazin-3-yl)-4-hydroxy-2-quinolones as HCV inhibitors.
The present invention is directed to compounds according to Formula I: 
wherein all represented groups are defined below.
The present invention is also directed to compounds of Formula I, or pharmaceutically acceptable salts or prodrugs thereof, which are useful as inhibitors of HCV NS5B RdRp. It is another object of the present invention to provide pharmaceutical compositions comprising a pharmaceutically acceptable carrier and a therapeutically effective amount of a compound of Formula I, or pharmaceutically acceptable salt or prodrug thereof. It is another object of the present invention to provide a method for the treatment or prevention of HCV comprising administering to a host in need of such treatment a therapeutically effective amount of a compound of Formula I, or a pharmaceutically acceptable salt or prodrug thereof. These and other objects of the invention, which will become apparent during the following detailed description, have been achieved by the discovery that compounds of Formula I inhibit the HCV NS5B RdRp.
The present invention is directed to compounds according to Formula I: 
wherein: Q is CH or N; R1 is tetrazolyl, MeCONHSO2xe2x80x94, PhCONHSO2xe2x80x94, R5O2C(CH2)0-3CONHSO2xe2x80x94, 
xe2x80x94CH2Ar1, xe2x80x94CHPh2, xe2x80x94CH2CO(4-FPh), xe2x80x94CH2CO(4-CF3Ph), or xe2x80x94CH2CONp where Np is naphthyl; R3 is C5-7cycloalkyl; R4 is hydrogen, Ar2, or Ar3; Ar1 is selected from the following group: phenyl, halophenyl, 
Ar2 is phenyl, naphthyl, or biphenyl, optionally substituted with 1-3 substituents selected from the group comprising halogen, C1-6 alkyl, hydroxy C1-6alkyl, C1-6alkoxy, C1-6sulfoxy, C1-2perfluoroalkyl, hydroxy, formyl, C1-6alkylcarbonyl, cyano, nitro, C1-6alkylamido, CO2R5, CONR5R5, C1-6alkylsulfonamido, and dioxolane; Ar3 is thienyl, furanyl, pyrrolyl, benzothiophenyl, benzofuranyl, indolyl, quinolinyl, or pyrimidinyl optionally substituted with 1-2 substituents selected from the group comprising C1-6alkyl, formyl, acetoxy, trifluoroacetoxy, and t-butoxycarbonyl; R5 is hydrogen or C1-6alkyl; R6 is halogen, methoxy, CO2R5 or CONR7R8; R7 and R8 are independently hydrogen, C1-6alkyl, xe2x80x94CH(Me)CO2R5, xe2x80x94(CH2)1-3CO2R5, xe2x80x94(CH2)1-3CONR5R5, xe2x80x94(CH2)1-3OH, 
or R7 and R8 taken together with the nitrogen to which they are attached form pyrrolidine, morpholine, piperidine, 4-hydroxypiperidine, piperazine, or 4-methylpiperazine; or a pharmaceutically acceptable salt, solvate, or prodrug thereof.
As used herein, the following terms shall be understood to have the meaning set forth in the following definitions.
The term xe2x80x9ccompounds of the inventionxe2x80x9d, and equivalent expressions, are meant to embrace compounds of formula I, and include prodrugs, pharmaceutically acceptable salts, and solvates, e.g. hydrates. Similarly, reference to intermediates, whether or not they themselves are claimed, is meant to embrace their salts, and solvates, where the context so permits.
The term xe2x80x9cderivativexe2x80x9d means a chemically modified compound wherein the modification is considered routine by the ordinary skilled chemist, such as an ester or an amide of an acid, protecting groups, such as a benzyl group for an alcohol or thiol, and tert-butoxycarbonyl group for an amine.
The term xe2x80x9canalogxe2x80x9d means a compound which comprises a chemically modified form of a specific compound or class thereof, and which maintains the pharmaceutical and/or pharmacological activities characteristic of said compound or class.
The term xe2x80x9csolvatexe2x80x9d means a physical association of a compound of this invention with one or more solvent molecules. This physical association includes hydrogen bonding. In certain instances the solvate will be capable of isolation, for example when one or more solvent molecules are incorporated in the crystal lattice of the crystalline solid. xe2x80x9cSolvatexe2x80x9d encompasses both solution-phase and isolable solvates. Exemplary solvates include hydrates, ethanolates, methanolates, and the like.
The term xe2x80x9ceffective amountxe2x80x9d means an amount of a compound/composition according to the present invention effective in producing the desired therapeutic effect, i.e. inhibiting HCV.
The term xe2x80x9cpatientxe2x80x9d includes both human and other mammals.
The term xe2x80x9cpharmaceutical compositionxe2x80x9d means a composition comprising a compound of formula I in combination with at least one additional pharmaceutical adjuvant, excipient, vehicle or carrier component, such as diluents, preserving agents, fillers, flow regulating agents, disintegrating agents, wetting agents, emulsifying agents, suspending agents, sweetening agents, flavoring agents, perfuming agents, antibacterial agents, antifungal agents, lubricating agents and dispensing agents, depending on the nature of the mode of administration and dosage forms. Any ingredient listed in Remington""s Pharmaceutical Sciences, 18th ed., Mack Publishing Company, may be used.
The term xe2x80x9calkylxe2x80x9d is intended to include both branched and straight-chain saturated aliphatic hydrocarbon groups having the specified number of carbon atoms. Thus, C1-6 alkyl refers to an alkyl group having from one to six carbon atoms. Examples of alkyl include, but are not limited to, methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, and t-butyl, pentyl, hexyl, heptyl and octyl.
The terms xe2x80x9clinear and cyclic heteroalkylxe2x80x9d are defined in accordance with the term xe2x80x9calkylxe2x80x9d with the suitable replacement of carbon atoms with an atom such as oxygen, nitrogen or sulfur which would render a chemically stable species.
The term xe2x80x9cheterocyclic C1-6 alkyl group means a C1-6 alkyl that is substituted by a heterocyclic group.
The terms xe2x80x9chaloxe2x80x9d or xe2x80x9chalogenxe2x80x9d as used herein refer to fluoro, chloro, bromo and iodo.
Alkanoyl refers to a substituent group having a C1-6 alkyl component bonded to a carbonyl group which is then bonded to the backbone to which the substituent group is connected.
The term xe2x80x9calkoxyxe2x80x9d is intended to represent an alkyl group with the indicated number of carbon atoms attached to an oxygen atom. Examples of alkoxy include, but are not limited to, methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, s-butoxy, and t-butoxy.
The term xe2x80x9carylxe2x80x9d is intended to mean an aromatic moiety containing the specified number of carbon atoms, such as, but not limited to phenyl, indanyl or naphthyl. So C6-14 aryl refers to an aromatic moiety having from six to fourteen carbon atoms which may be in the form of a single, bicyclic or tricyclic structure. The term xe2x80x9chaloarylxe2x80x9d as used herein refers to an aryl mono, di or tri substituted with halogen atoms.
As used herein, the term xe2x80x9ccycloalkylxe2x80x9d refers to a saturated monocyclic alkyl group. Examples of such carbocycles include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl.
As used herein, the term xe2x80x9cheterocyclexe2x80x9d or xe2x80x9cheterocyclic systemxe2x80x9d is intended to mean a stable 5- to 7-membered monocyclic or bicyclic or 7- to 14-membered bicyclic heterocyclic ring which is saturated, partially unsaturated or unsaturated (aromatic), and which consists of carbon atoms and from 1 to 4 heteroatoms independently selected from the group consisting of N, O and S and including any bicyclic group in which any of the above-defined heterocyclic rings is fused to a benzene ring. The nitrogen and sulfur heteroatoms may optionally be oxidized. The heterocyclic ring may be attached to its pendant group at any heteroatom or carbon atom which results in a stable structure. The heterocyclic rings described herein may be substituted on carbon or on a nitrogen atom if the resulting compound is stable. If specifically noted, a nitrogen in the heterocycle may optionally be quaternized. It is preferred that when the total number of S and O atoms in the heterocycle exceeds 1, then these heteroatoms are not adjacent to one another. It is preferred that the total number of S and O atoms in the heterocycle is not more than 2. Also included are fused ring and spiro compounds containing, for example, the above heterocycles.
The term xe2x80x9caromatic heterocyclic systemxe2x80x9d or xe2x80x9cheteroarylxe2x80x9d means a stable 5- to 7-membered monocyclic or bicyclic or 7- to 10-membered bicyclic heterocyclic aromatic ring which consists of carbon atoms and from 1 to 4 heterotams independently selected from the group consisting of N, O and S. The term includes any bicyclic group in which any of the above-defined heterocyclic rings is fused to a benzene ring. It is preferred that the total number of S and O atoms in the aromatic heterocycle is not more than 2.
Examples of heterocycles include, but are not limited to, piperidinyl, morpholinyl, piperazinyl, 1H-indazole, 2-pyrrolidonyl, 2H,6H-1,5,2-dithiazinyl, 2H-pyrrolyl, 3H-indolyl, 4-piperidonyl, 4aH-carbazole, 4H-quinolizinyl, 6H-1,2,5-thiadiazinyl, acridinyl, azocinyl, benzimidazolyl, benzofuranyl, benzothiofuranyl, benzothiophenyl, benzoxazolyl, benzthiazolyl, benztriazolyl, benztetrazolyl, benzisoxazolyl, benzisothiazolyl, benzimidazalonyl, carbazolyl, 4aH-carbazolyl, b-carbolinyl, chromanyl, chromenyl, cinnolinyl, decahydroquinolinyl, 2H,6H-1,5,2-dithiazinyl, dihydrofuro[2,3-b]tetrahydrofuran, furanyl, furazanyl, imidazolidinyl, imidazolinyl, imidazolyl, 1H-indazolyl, indolenyl, indolinyl, indolizinyl, indolyl, isobenzofuranyl, isochromanyl, isoindazolyl, isoindolinyl, isoindolyl, isoquinolinyl, isothiazolyl, isoxazolyl, morpholinyl, naphthyridinyl, octahydroisoquinolinyl, oxadiazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, oxazolidinyl, oxazolyl, oxazolidinylperimidinyl, phenanthridinyl, phenanthrolinyl, phenarsazinyl, phenazinyl, phenothiazinyl, phenoxathiinyl, phenoxazinyl, phthalazinyl, piperazinyl, piperidinyl, pteridinyl, piperidonyl, 4-piperidonyl, pteridinyl, purinyl, pyranyl, pyrazinyl, pyrazolidinyl, pyrazolinyl, pyrazolyl, pyridazinyl, pyridooxazole, pyridoimidazole, pyridothiazole, pyridinyl, pyridyl, pyrimidinyl, pyrrolidinyl, pyrrolinyl, pyrrolyl, quinazolinyl, quinolinyl, 4H-quinolizinyl, quinoxalinyl, quinuclidinyl, carbolinyl, tetrahydrofuranyl, tetrahydroisoquinolinyl, tetrahydroquinolinyl, 6H-1,2,5-thiadiazinyl, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl, 1,3,4-thiadiazolyl, thianthrenyl, thiazolyl, thienyl, thienothiazolyl, thienooxazolyl, thienoimidazolyl, thiophenyl, triazinyl, 1,2,3-triazolyl, 1,2,4-triazolyl, 1,2,5-triazolyl, 1,3,4-triazolyl, xanthenyl. Preferred heterocycles include, but are not limited to, pyridinyl, furanyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, indolyl, benzimidazolyl, 1H-indazolyl, oxazolidinyl, benzotriazolyl, benzisoxazolyl, oxindolyl, benzoxazolinyl, or isatinoyl.
As used herein, xe2x80x9cpharmaceutically acceptable saltsxe2x80x9d refer to derivatives of the disclosed compounds wherein the parent compound is modified by making acid or base salts thereof. Examples of pharmaceutically acceptable salts include, but are not limited to, mineral or organic acid salts of basic residues such as amines; alkali or organic salts of acidic residues such as carboxylic acids; and the like. The pharmaceutically acceptable salts include the conventional non-toxic salts or the quaternary ammonium salts of the parent compound formed, for example, from non-toxic inorganic or organic acids. For example, such conventional non-toxic salts include those derived from inorganic acids such as hydrochloric, hydrobromic, sulfuric, sulfamic, phosphoric, nitric and the like; and the salts prepared from organic acids such as acetic, propionic, succinic, glycolic, stearic, lactic, malic, tartaric, citric, ascorbic, palmitic, maleic, hydroxymaleic, phenylacetic, glutamic, benzoic, salicylic, sulfanilic, 2-acetoxybenzoic, fumaric, toluenesulfonic, methanesulfonic, ethane disulfonic, oxalic, isethionic, and the like.
The pharmaceutically acceptable salts of the present invention can be synthesized from the parent compound which contains a basic or acidic moiety by conventional chemical methods. Generally, such salts can be prepared by reacting the free acid or base forms of these compounds with a stoichiometric amount of the appropriate base or acid in water or in an organic solvent, or in a mixture of the two; generally, nonaqueous media like ether, ethyl acetate, ethanol, isopropanol, or acetonitrile are preferred. Lists of suitable salts are found in Remington""s Pharmaceutical Sciences, 18th ed., Mack Publishing Company, Easton, Pa., 1990, p. 1445, the disclosure of which is hereby incorporated by reference.
The compounds of the present invention are useful in the form of the free base or acid or in the form of a pharmaceutically acceptable salt thereof. All forms are within the scope of the invention.
The phrase xe2x80x9cpharmaceutically acceptablexe2x80x9d is employed herein to refer to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication commensurate with a reasonable risk/benefit ratio.
The term xe2x80x9cpharmaceutically acceptable prodrugsxe2x80x9d as used herein means those prodrugs of the compounds useful according to the present invention which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of humans and lower animals without undue toxicity, irritation, allergic response, and the like, commensurate with a reasonable risk/benefit ratio, and effective for their intended use, as well as zwitterionic forms, where possible, of the compounds of the invention.
The term xe2x80x9cprodrugsxe2x80x9d, as the term is used herein, are intended to include any covalently bonded carriers which release an active parent drug of the present invention in vivo when such prodrug is administered to a mammalian subject. Since prodrugs are known to enhance numerous desirable qualities of pharmaceuticals (i.e., solubility, bioavailability, manufacturing, etc.) the compounds of the present invention may be delivered in prodrug form. Thus, the skilled artisan will appreciate that the present invention encompasses prodrugs of the presently claimed compounds, methods of delivering the same, and compositions containing the same. Prodrugs of the present invention are prepared by modifying functional groups present in the compound in such a way that the modifications are cleaved, either in routine manipulation or in vivo, to form the parent compound. The transformation in vivo may be, for example, as the result of some metabolic process, such as chemical or enzymatic hydrolysis of a carboxylic, phosphoric or sulphate ester, or reduction or oxidation of a susceptible functionality. Prodrugs include compounds of the present invention wherein a hydroxy, amino, or sulfhydryl group is bonded to any group that, when the prodrug of the present invention is administered to a mammalian subject, it cleaves to form a free hydroxyl, free amino, or free sulfydryl group, respectively. Functional groups which may be rapidly transformed, by metabolic cleavage, in vivo form a class of groups reactive with the carboxyl group of the compounds of this invention. They include, but are not limited to such groups as alkanoyl (such as acetyl, propionyl, butyryl, and the like), unsubstituted and substituted aroyl (such as benzoyl and substituted benzoyl), alkoxycarbonyl (such as ethoxycarbonyl), trialkylsilyl (such as trimethyl- and triethysilyl), monoesters formed with dicarboxylic acids (such as succinyl), and the like. Because of the ease with which the metabolically cleavable groups of the compounds useful according to this invention are cleaved in vivo, the compounds bearing such groups can act as pro-drugs. The compounds bearing the metabolically cleavable groups have the advantage that they may exhibit improved bioavailability as a result of enhanced solubility and/or rate of absorption conferred upon the parent compound by virtue of the presence of the metabolically cleavable group. A thorough discussion of prodrugs is provided in the following: Design of Prodrugs, H. Bundgaard, ed., Elsevier, 1985; Methods in Enzymology, K. Widder et al, Ed., Academic Press, 42, p.309-396, 1985; A Textbook of Drug Design and Development, Krogsgaard-Larsen and H. Bundgaard, ed., Chapter 5; xe2x80x9cDesign and Applications of Prodrugsxe2x80x9d p.113-191, 1991; Advanced Drug Delivery Reviews, H. Bundgard, 8, p.1-38, 1992; Journal of Pharmaceutical Sciences, 77, p. 285, 1988; Chem. Pharm. Bull., N. Nakeya et al, 32, p. 692, 1984; Pro-drugs as Novel Delivery Systems, T. Higuchi and V. Stella, Vol. 14 of the A.C.S. Symposium Series, and Bioreversible Carriers in Drug Design, Edward B. Roche, ed., American Pharmaceutical Association and Pergamon Press, 1987, each of which is herein incorporated by reference in their entirety as though set forth in full.
The term xe2x80x9ctreatingxe2x80x9d refers to: (i) preventing a disease, disorder or condition from occurring in an animal which may be predisposed to the disease, disorder and/or condition but has not yet been diagnosed as having it; (ii) inhibiting the disease, disorder or condition, i.e., arresting its development; and (iii) relieving the disease, disorder or condition, i.e., causing regression of the disease, disorder and/or condition.
Certain compounds of Formula I and intermediates used in making these compounds may exhibit tautomerism and in some cases one tautomer has been schematically drawn to represent all forms. Certain compounds of formula I can exhibit isomerism, for example geometrical isomerism, e.g., E or Z isomerism, and optical isomerism, e.g., R or S configurations. Geometrical isomers include the cis and trans forms of compounds of the invention having alkenyl moieties. It is well known in the art how to prepare optically active forms, such as by resolution of racemic forms or by synthesis from optically active starting materials. All chiral, diastereomeric, racemic forms and all geometric isomeric forms of a structure are intended, unless the specific stereochemistry or isomer form is specifically indicated.
Such isomers can be separated from their mixtures, by the application or adaptation of known methods, for example chromatographic techniques and recrystallization techniques, or they are separately prepared from the appropriate isomers of their intermediates, for example by the application or adaptation of methods described herein.
Where the compound of the present invention is substituted with a basic moiety, acid addition salts are formed and are simply a more convenient form for use; and in practice, use of the salt form inherently amounts to use of the free base form. The acids which can be used to prepare the acid addition salts include preferably those which produce, when combined with the free base, pharmaceutically acceptable salts, that is, salts whose anions are non-toxic to the patient in pharmaceutical doses of the salts, so that the beneficial inhibitory effects on HCV RdRp inherent in the free base are not vitiated by side effects ascribable to the anions. Although pharmaceutically acceptable salts of said basic compounds are preferred, all acid addition salts are useful as sources of the free base form even if the particular salt, per se, is desired only as an intermediate product as, for example, when the salt is formed only for purposes of purification, and identification, or when it is used as an intermediate in preparing a pharmaceutically acceptable salt by ion exchange procedures.
According to a further feature of the invention, acid addition salts of the compounds of this invention are prepared by reaction of the free base with the appropriate acid, by the application or adaptation of known methods. For example, the acid addition salts of the compounds of this invention are prepared either by dissolving the free base in aqueous or aqueous-alcohol solution or other suitable solvents containing the appropriate acid and isolating the salt by evaporating the solution, or by reacting the free base and acid in an organic solvent, in which case the salt separates directly or can be obtained by concentration of the solution.
The acid addition salts of the compounds of this invention can be regenerated from the salts by the application or adaptation of known methods. For example, parent compounds of the invention can be regenerated from their acid addition salts by treatment with an alkali, e.g. aqueous sodium bicarbonate solution or aqueous ammonia solution.
Where the compound of the invention is substituted with an acidic moiety, base addition salts may be formed and can be simply a more convenient form for use; and in practice, use of the salt form inherently amounts to use of the free acid form. The bases which can be used to prepare the base addition salts include those which produce, when combined with the free acid, pharmaceutically acceptable salts, that is, salts whose cations are non-toxic to the animal organism in pharmaceutical doses of the salts, so that the beneficial inhibitory effects on HCV RdRp inherent in the free acid are not vitiated by side effects ascribable to the cations. Pharmaceutically acceptable salts, including for example alkali and alkaline earth metal salts, within the scope of the invention are those derived from the following bases: sodium hydride, sodium hydroxide, potassium hydroxide, calcium hydroxide, aluminum hydroxide, lithium hydroxide, magnesium hydroxide, zinc hydroxide, ammonia, ethylenediamine, N-methyl-glucamine, lysine, arginine, ornithine, choline, N,Nxe2x80x2-dibenzylethylenediamine, chloroprocaine, diethanolamine, procaine, N-benzylphenethylamine, diethylamine, piperazine, tris(hydroxymethyl)-aminomethane, tetramethylammonium hydroxide, and the like.
Metal salts of compounds of the present invention may be obtained by contacting a hydride, hydroxide, carbonate or similar reactive compound of the chosen metal in an aqueous or organic solvent with the free acid form of the compound. The aqueous solvent employed may be water or it may be a mixture of water with an organic solvent, preferably an alcohol such as methanol or ethanol, a ketone such as acetone, an aliphatic ether such as tetrahydrofuran, or an ester such as ethyl acetate. Such reactions are normally conducted at ambient temperature but they may, if desired, be conducted with heating.
Amine salts of compounds of the present invention may be obtained by contacting an amine in an aqueous or organic solvent with the free acid form of the compound. Suitable aqueous solvents include water and mixtures of water with alcohols such as methanol or ethanol, ethers such as tetrahydrofuran, nitrites such as acetonitrile, or ketones such as acetone. Amino acid salts may be similarly prepared.
The base addition salts of the compounds of this invention can be regenerated from the salts by the application or adaptation of known methods. For example, parent compounds of the invention can be regenerated from their base addition salts by treatment with an acid, e.g. hydrochloric acid.
Pharmaceutically acceptable salts also include quaternary lower alkyl ammonium salts. The quaternary salts are prepared by the exhaustive alkylation of basic nitrogen atoms in compounds, including nonaromatic and aromatic basic nitrogen atoms, according to the invention, i.e., alkylating the non-bonded pair of electrons of the nitrogen moieties with an alkylating agent such as methylhalide, particularly methyl iodide, or dimethyl sulfate. Quaternarization results in the nitrogen moiety becoming positively charged and having a negative counter ion associated therewith.
As will be self-evident to those skilled in the art, some of the compounds of this invention do not form stable salts. However, acid addition salts are more likely to be formed by compounds of this invention having a nitrogen-containing heteroaryl group and/or wherein the compounds contain an amino group as a substituent. Preferable acid addition salts of the compounds of the invention are those wherein there is not an acid labile group.
As well as being useful in themselves as active compounds, salts of compounds of the invention are useful for the purposes of purification of the compounds, for example by exploitation of the solubility differences between the salts and the parent compounds, side products and/or starting materials, by techniques well known to those skilled in the art.
Compounds according to the invention, for example, starting materials, intermediates or products, are prepared as described herein or by the application or adaptation of known methods, by which is meant methods used heretofore or described in the literature, for example those described by R. C. Larock in Comprehensive Organic Transformations, VCH publishers, 1989.
In the reactions described hereinafter it may be necessary to protect reactive functional groups, for example hydroxy, amino, imino, thio or carboxy groups, where these are desired in the final product, to avoid their unwanted participation in the reactions. Conventional protecting groups may be used in accordance with standard practice, for examples see T. W. Green and P. G. M. Wuts in xe2x80x9cProtective Groups in Organic Chemistryxe2x80x9d John Wiley and Sons, 1991; J. F. W. McOmie in xe2x80x9cProtective Groups in Organic Chemistryxe2x80x9d Plenum Press, 1973.
The compounds useful according to the invention optionally are supplied as salts. Those salts which are pharmaceutically acceptable are of particular interest since they are useful in administering the foregoing compounds for medical purposes. Salts which are not pharmaceutically acceptable are useful in manufacturing processes, for isolation and purification purposes, and in some instances, for use in separating stereoisomeric forms of the compounds of this invention. The latter is particularly true of amine salts prepared from optically active amines.
Where the compound useful according to the invention contains a carboxy group, or a sufficiently acidic bioisostere, base addition salts may be formed and are simply a more convenient form for use; and in practice, use of the salt form inherently amounts to use of the free acid form.
Also, where the compound useful according to the invention contains a basic group, or a sufficiently basic bioisostere, acid addition salts may be formed and are simply a more convenient form for use; and in practice, use of the salt form inherently amounts to use of the free base form.
The foregoing compounds useful according to the invention may also be combined with another therapeutic compound to form pharmaceutical compositions (with or without diluent or carrier) which, when administered, provide simultaneous administration of two or more active ingredients resulting in the combination therapy of the invention.
While it is possible for compounds useful according to the invention to be administered alone it is preferable to present them as pharmaceutical compositions. The pharmaceutical compositions, both for veterinary and for human use, useful according to the present invention comprise at lease one compound of the invention, as above defined, together with one or more acceptable carriers therefor and optionally other therapeutic ingredients. The skilled artisan will appreciate the abundance of publications setting forth the state of the art for pharmaceutical administration.
Examples of suspending agents include ethoxylated isostearyl alcohols, polyoxyethylene sorbitol and sorbitan esters, microcrystalline cellulose, aluminum metahydroxide, bentonite, agar-agar and tragacanth, or mixtures of these substances. Prevention of the action of microorganisms can be ensured by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, sorbic acid, and the like. It may also be desirable to include isotonic agents, for example sugars, sodium chloride and the like. Prolonged absorption of the injectable pharmaceutical form can be brought about by the use of agents delaying absorption, for example, aluminum monosterate and gelatin. Examples of suitable carriers, diluents, solvents or vehicles include water, ethanol, polyols, suitable mixtures thereof, vegetable oils (such as olive oil) and injectable organic esters such as ethyl oleate. Examples of excipients include lactose, milk sugar, sodium citrate, calcium carbonate, dicalcium phosphate phosphate. Examples of disintegrating agents include starch, alginic acids and certain complex silicates. Examples of lubricants include magnesium stearate, sodium lauryl sulphate, talc, as well as high molecular weight polyethylene glycols.
In certain preferred embodiments, active ingredients necessary in combination therapy may be combined in a single pharmaceutical composition for simultaneous administration.
The choice of vehicle and the content of active substance in the vehicle are generally determined in accordance with the solubility and chemical properties of the active compound, the particular mode of administration and the provisions to be observed in pharmaceutical practice. For example, excipients such as lactose, sodium citrate, calcium carbonate, dicalcium phosphate and disintegrating agents such as starch, alginic acids and certain complex silicates combined with lubricants such as magnesium stearate, sodium lauryl sulphate and talc may be used for preparing tablets. To prepare a capsule, it is advantageous to use lactose and high molecular weight polyethylene glycols. When aqueous suspensions are used they can contain emulsifying agents or agents which facilitate suspension. Diluents such as sucrose, ethanol, polyethylene glycol, propylene glycol, glycerol and chloroform or mixtures thereof may also be used.
The oily phase of the emulsions of this invention may be constituted from known ingredients in a known manner. While the oily phase may comprise merely an emulsifier (otherwise known as an emulgent), it desirably comprises a mixture of at least one emulsifier with a fat or an oil or with both a fat and an oil. Preferably, a hydrophilic emulsifier is included together with a lipophilic emulsifier which acts as a stabilizer. It is also preferred to include both an oil and a fat. Together, the emulsifier(s) with or without stabilizer(s) make up the emulsifying wax, and the wax together with the oil and fat make up the emulsifying ointment base which forms the oily dispersed phase of a cream formulation. Emulgents and emulsion stabilizers suitable for use in the formulation of the present invention include Tween(copyright) 60, Span(copyright) 80, cetostearyl alcohol, benzyl alcohol, myristyl alcohol, glyceryl mono-stearate and sodium lauryl sulfate.
If desired, the aqueous phase of the cream base may include, for example, a least 30% w/w of a polyhydric alcohol, i.e. an alcohol having two or more hydroxyl groups such as propylene glycol, butane 1,3-diol, mannitol, sorbitol, glycerol and polyethylene glycol (including PEG 400) and mixtures thereof. The topical formulations may desirably include a compound which enhances absorption or penetration of the active ingredient through the skin or other affected areas. Examples of such dermal penetration enhancers include dimethyl sulphoxide and related analogues.
The choice of suitable oils or fats for the formulation is based on achieving the desired cosmetic properties. Thus the cream should preferably be a non-greasy, non-staining and washable product with suitable consistency to avoid leakage from tubes or other containers. Straight or branched chain, mono- or dibasic alkyl esters such as di-isopropyl myristate, decyl oleate, isopropyl palmitate, butyl stearate, 2-ethylhexyl palmitate or a blend of branched chain esters known as Crodamol CAP may be used, the last three being preferred esters. These may be used alone or in combination depending on the properties required. Alternatively, high melting point lipids such as white soft paraffin and/or liquid paraffin or other mineral oils can be used. Solid compositions may also be employed as fillers in soft and hard-filled gelatin capsules using such excipients as lactose or milk sugar as well as high molecular weight polyethylene glycols, and the like.
The pharmaceutical compositions can be administered in a suitable formulation to humans and animals by topical or systemic administration, including oral, inhalational, rectal, nasal, buccal, sublingual, vaginal, parenteral (including subcutaneous, intramuscular, intravenous, intradermal, intrathecal and epidural), intracisternal and intraperitoneal. It will be appreciated that the preferred route may vary with for example the condition of the recipient.
The formulations can be prepared in unit dosage form by any of the methods well known in the art of pharmacy. Such methods include the step of bringing into association the active ingredient with the carrier which constitutes one or more accessory ingredients. In general the formulations are prepared by uniformly and intimately bringing into association the active ingredient with liquid carriers or finely divided solid carriers or both, and then, if necessary, shaping the product.
A tablet may be made by compression or moulding, optionally with one or more accessory ingredients. Compressed tables may be prepared by compressing in a suitable machine the active ingredient in a free-flowing form such as a powder or granules, optionally mixed with a binder, lubricant, inert diluent, preservative, surface active or dispersing agent. Moulded tablets may be made by moulding in a suitable machine a mixture of the powdered compounds moistened with an inert liquid diluent. The tablets may optionally be coated or scored and may be formulated so as to provide slow or controlled release of the active ingredient therein.
Solid compositions for rectal administration include suppositories formulated in accordance with known methods and containing at least one compound of the invention.
If desired, and for more effective distribution, the compounds can be microencapsulated in, or attached to, a slow release or targeted delivery systems such as a biocompatible, biodegradable polymer matrices (e.g. poly(d,1-lactide co-glycolide)), liposomes, and microspheres and subcutaneously or intramuscularly injected by a technique called subcutaneous or intramuscular depot to provide continuous slow release of the compound(s) for a period of 2 weeks or longer. The compounds may be sterilized, for example, by filtration through a bacteria retaining filter, or by incorporating sterilizing agents in the form of sterile solid compositions which can be dissolved in sterile water, or some other sterile injectable medium immediately before use.
Actual dosage levels of active ingredient in the compositions of the invention may be varied so as to obtain an amount of active ingredient that is effective to obtain a desired therapeutic response for a particular composition and method of administration. The selected dosage level therefore depends upon the desired therapeutic effect, on the route of administration, on the desired duration of treatment and other factors.
Total daily dose of the compounds useful according to this invention administered to a host in single or divided doses may be in amounts, for example, of from about 0.0001 to about 100 mg/kg body weight daily and preferably 0.01 to 10 mg/kg/day. Dosage unit compositions may contain such amounts of such submultiples thereof as may be used to make up the daily dose. The skilled artisan will appreciate that the specific dose level for any particular patient will depend upon a variety of factors including the patient""s body weight, general health, sex, diet, time and route of administration, rates of absorption and excretion, combination with other drugs and the severity of the particular disease being treated.
The amount of each component administered is determined by the attending clinicians taking into consideration the etiology and severity of the disease, the patient""s condition and age, the potency of each component and other factors.
The formulations may be presented in unit-dose or multi-dose containers, for example sealed ampoules and vials with elastomeric stoppers, and may be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example water for injections, immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules and tablets of the kind previously described.
Administration of a compound of the present invention in combination with additional therapeutic agents, may afford an efficacy advantage over the compounds and agents alone, and may do so while permitting the use of lower doses of each. A lower dosage minimizes the potential of side effects, thereby providing an increased margin of safety. The combination of a compound of the present invention with such additional therapeutic agents is preferably a synergistic combination. Synergy, as described for example by Chou and Talalay, Adv. Enzyme Regul. 22:27-55 (1984), occurs when the therapeutic effect of the compound and agent when administered in combination is greater than the additive effect of either the compound or agent when administered alone. In general, a synergistic effect is most clearly demonstrated at levels that are (therapeutically) sub-optimal for either the compound of the present invention or a known antiviral agent alone, but which are highly efficacious in combination. Synergy can be in terms of improved inhibitory response without substantial increases in toxicity over individual treatments alone, or some other beneficial effect of the combination compared with the individual components.
Procedures for evaluating the biological activity of compounds or compositions according to the invention are carried out as described herein or by the application or adaptation of procedures well known in the art as described in the literature. The compounds of the present invention, their methods or preparation and their biological activity will appear more clearly from the examination of the following examples which are presented as an illustration only and are not to be considered as limiting the invention in its scope. The following examples are but preferred methods of synthesizing the compounds of the invention, which may be prepared according to any method known to the organic chemist of ordinary skill. Other features of the invention will become apparent during the following descriptions of exemplary embodiments which are given for illustration of the invention and are not intended to be limiting thereof. Each of the patents, patent applications, and other cited references, are hereby incorporated herein by reference in their entity as though set forth in full.
The compounds of the present invention can be prepared in a number of ways well known to one skilled in the art of organic synthesis. The compounds of the present invention can be synthesized using the methods described below, together with methods known in the art of synthetic organic chemistry, or variations thereon as appreciated by those skilled in the art. A particularly useful compendium of synthetic methods which may be applicable to the preparation of compounds of the present invention may be found in Larock, R. C. Comprehensive Organic Transformations, VCH: New York, 1989. Preferred methods include, but are not limited to, those described below. All references cited herein are hereby incorporated in their entirety herein by reference.
The novel compounds of this invention may be prepared using the reactions and techniques described in this section. The reactions are performed in solvents appropriate to the reagents and materials employed and are suitable for the transformations being effected. Also, in the description of the synthetic methods described below, it is to be understood that all proposed reaction conditions, including choice of solvent, reaction atmosphere, reaction temperature, duration of the experiment and workup procedures, are chosen to be the conditions standard for that reaction, which should be readily recognized by one skilled in the art. It is understood by one skilled in the art of organic synthesis that the functionality present on various portions of the molecule must be compatible with the reagents and reactions proposed. Such restrictions to the substituents which are compatible with the reaction conditions will be readily apparent to one skilled in the art and alternate methods must then be used. In addition, it may be necessary to introduce or remove protecting groups in order to carry certain substituents through the indicated reaction conditions. A compendium of protecting groups which may be useful, together with reaction conditions for introduction and removal may be found in Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic Synthesis, Second Edition; Wiley: New York, 1991.
The starting materials and all reagents and intermediates for these synthetic routes are either commercially available or may be prepared by methods known to one skilled in the art of organic synthesis from commercially available materials.
The following methods describe different preparations of the compounds of the present invention. The methods are often general in nature and may be used to make variations of the inventive embodiments. Other variations would be apparent to those skilled in the art.
Method A describes a general method of preparing compounds of Formula I (Scheme 1). Amine 3 is produced by nucleophilic displacement of aryl chloride 1 by cyclohexylamine (2). Reduction of the nitro group of 3 produces amine 4 which is condensed with imidate 5 to provide benzimidazole 6. The phenol of 6 can be alkylated with a variety of agents to form Formula I compounds. These agents include diphenylmethylbromide (7) which generates nitrile 8. Transformation of the nitrile moiety of 8 to a tetrazole yields 9, an example of a Formula I compound.
Additionally, the nitrile of 8 may be converted to a 5-oxo-1,2,4-oxadiazole by reaction with hydroxylamine followed by reaction with methylchloroformate or carbonyldiimidazole. The nitrile may also be converted to a 2-oxo-1,2,3,5-oxathiadiazole by reaction with hydroxylamine followed by reaction with thionyl chloride and pyridine. 
Method B provides an alternative method of preparing Formula I compounds (Scheme 2). Amine 4 can be condensed with a range of acid chlorides including 10 to form amides such as 11 which are cyclized to form benzimidazoles of which 12 is a representative example. Conversion of the nitrile moiety of 12 into a tetrazole provides compound 13, which is an example of a Formula I compound. 
Method C describes an additional alkylative preparation of a Formula I compound. The alkylating agent 14 is prepared by coupling 4-chlorophenylboronic acid with 2-bromo-5-methoxytoluene which is in turn brominated on the tolyl methyl group. Many of the benzyl-type alkylating agents can be prepared by this route. 
Method D provides an alternative route to Formula I compounds and describes the preparation of compounds where R2 is xe2x80x94CH2C6H3R4R6 and R4 is Ar2 or Ar3 (Scheme 4). Phenol 6 is protected as the tert-butyldimethylsilyl (TBDMS) ether 20. The nitrile moiety of 20 is then converted to tetrazole 21 and the tetrazole protected with a trityl group. Subsequent removal of the TBDMS protecting group with tetrabutylammonium fluoride (TBAF) affords intermediate 22 which is alkylated with a 3-bromomethyl-4-bromo benzoate ester (with, for example, R=methyl or tert-butyl). Reasonable variations of this agent (for example with a triflate replacing the aryl bromide or substituting a close analog of the alkyl ester) would be known to those skilled in the art. The resulting intermediate 23 may be used as a coupling partner with various organometallic compounds to afford compounds similar to 25. Trityl deprotection affords ester 26. Hydrolysis of this ester provides acids also of Formula 26 (Rxe2x95x90H). The esters and acids are examples of Formula I compounds. 
Method E describes the use of solid phase technology for the preparation of compounds of Formula I (Scheme 5). Phenol 27 is attached to a polymeric support, such as the Merrifield resin, and converted into an appropriate linker such as 30. Intermediate tetrazole 21 is then tethered to this linker. Deprotection and alkylation as described previously provide compounds like 34a. Cleavage from the resin affords compound 34, which is an example of a Formula I compounds. 
Method F provides an additional solid phase approach which utilizes chloro trityl resin 35 (scheme 6). 
Method G provides for a preparation of Formula I compounds where R6 is CONR7R8 (scheme 7). Tetrazole 23 can be coupled with a variety of organometallic compounds to afford compounds like 39. Hydrolysis of the methyl ester of 39 gives carboxylic acid 40. The carboxylic acid moiety is transformed to an amide using amines of Formula HNR7R8. In this scheme the amine is an alkyl ester of glycine, which is then hydrolyzed. The protecting group of 42 is then removed to provide compound 43. The esters, acids, and amides are examples of Formula I compounds. 
Method H provides a preparation of various R1 substituents (scheme 8). Compounds of Formula 48 may be made in an analogous fashion to those of Formula 8 or 12. By judicious choice of the ester moiety of 48, ester hydrolysis may be carried out under basic (R is methyl), acidic (R is t-butyl), or neutral (R is benzyl) conditions to provide compounds like 49. Acid 49 may be coupled with a sulfonamide via the acid chloride to provide compounds like 55. In a similar manner, other acylsulfonamides provide additional examples of Formula I compounds. 
Method I provides methods for making compounds where Q is N (scheme 9). Where appropriate, these methods may be used in the previous procedures to prepare other examples of formula I compounds. 
Method J provides a method for preparing Formula I compounds where R1 is a RCONHSO2xe2x80x94 moiety (Scheme 10).
The preparation of the primary sulfonamide 69 follows the previous methods. Acylation of the sulfonamide can be accomplished by treating the anion of the sulfonamide with an appropriate acylating agent. 
Abbreviations used in the examples are defined as follows: xe2x80x9c1xc3x97xe2x80x9d for once, xe2x80x9c2xc3x97xe2x80x9d for twice, xe2x80x9c3xc3x97xe2x80x9d for thrice, xe2x80x9crtxe2x80x9d for room temperature, xe2x80x9ceqxe2x80x9d for equivalent or equivalents, xe2x80x9cgxe2x80x9d for gram or grams, xe2x80x9cmgxe2x80x9d for milligram or milligrams, xe2x80x9cmLxe2x80x9d for milliliter or milliliters, xe2x80x9cMxe2x80x9d for molar, N for normal, xe2x80x9cmmolxe2x80x9d for millimole or millimoles, xe2x80x9cminxe2x80x9d for minute or minutes, xe2x80x9chxe2x80x9d for hour or hours, xe2x80x9cMSxe2x80x9d for mass spectrometry, xe2x80x9cESIxe2x80x9d for electrospray ionization, xe2x80x9cNMRxe2x80x9d for nuclear magnetic resonance spectroscopy, xe2x80x9c1Hxe2x80x9d for proton, xe2x80x9cxcex4xe2x80x9d for delta, xe2x80x9csxe2x80x9d for singlet, xe2x80x9cdxe2x80x9d for doublet, xe2x80x9ctxe2x80x9d for triplet, xe2x80x9cqxe2x80x9d for quartet, xe2x80x9cmxe2x80x9d for multiplet, xe2x80x9cbrxe2x80x9d for broad, xe2x80x9cHzxe2x80x9d for hertz, xe2x80x9cHPLCxe2x80x9d for high pressure liquid chromatography, xe2x80x9cELSDxe2x80x9d for evaporative light scattering detector, xe2x80x9ctlcxe2x80x9d for thin layer chromatography, xe2x80x9cv/vxe2x80x9d for volume to volume ratio, xe2x80x9catmxe2x80x9d for atmosphere, xe2x80x9cpsixe2x80x9d for pounds per square inch, xe2x80x9cxcex1xe2x80x9d, xe2x80x9cxcex2xe2x80x9d, xe2x80x9cRxe2x80x9d, and xe2x80x9cSxe2x80x9d are stereochemical designations familiar to one skilled in the art. DMF is N,N-dimethylformamide, THF is tetrahydrofuran. Temperatures are expressed in degrees Celsius.
The majority of the final compounds were purified by reverse phase chromatography using a preparative C-18 column employing gradients of methanolxe2x80x94water containing 0.1% of trifluoroacetic acid (TFA), and using a Shimadzu High Performance Liquid Preparative Chromatographic System employing an XTERRA 3.0xc3x9750 mm S7 column at 5 mL/min flow rate with a 2 min gradient. The final compounds were usually isolated and submitted for biological evaluations as their acid addition salts with trifluoroacetic acid. Molecular weights and purities were usually determined using a Shimadzu LCMS. NMR spectra were usually obtained on either a Bruker 500 or 300 MHz instrument.
A solution of 4-chloro-3-nitrobenzonitrile (5.28 g, 28.9 mmol), cyclohexylamine (5.0 mL, 43.7 mmol), and triethylamine (6.0 mL, 43.0 mL) in acetonitrile (75 mL) was stirred at 50xc2x0 C. for 15 h. The reaction mixture was cooled to rt and then poured into 100 mL ice water. The solid precipitate was filtered, washed with water, and dried to afford compound 3 as a yellow solid (6.42 g, 90%). ESI-MS m/e 246.3 (M+1).
A solution of compound 3 (1.23 g, 5.01 mmol) in ethyl acetate (30 mL) and methanol (10 mL) was hydrogenated over 10% palladium on carbon (0.11 g) at 20 psi for 1 h. The reaction mixture was filtered and concentrated on a rotary evaporator to give compound 4 (1.07 g, 99%) as a red-brown solid. ESI-MS m/e 216.3 (M+1).
A solution of ethyl 4-hydroxybenzimidate hydrochloride (5, 1.26 g, 6.7 mmol) and compound 4 (1.5 g, 5.0 mmol) in methanol (10 mL) was refluxed overnight under a nitrogen atmosphere. The reaction mixture was cooled to rt, filtered, and washed with methanol to afford 6 as a pinkish brown solid (1.26 g, 68%). ESI-MS m/e 372.1 (M+1).
A 60% dispersion of sodium hydride in mineral oil (50 mg, 1.25 mmol) was added in a single portion to a stirred mixture of compound 6 in DMF (3.5 mL). When the rapid evolution of hydrogen had ceased, the mixture was cooled in an ice-water bath. Diphenylmethyl bromide (297 mg, 1.2 mmol) was added. The mixture was stirred at an oil bath temperature of 55xc2x0 C. for 30 min. The mixture was cooled and poured into cold water to precipitate a solid. The solid was dried and crystallized from ethyl acetate-hexanes to afford 8 as off white needles. ESI-MS m/e 484 (M+1).